In utilizing the mentioned splice, the free ends of the two fibers are received in axial bores in two cylindrical glass ferrules or plugs to extend slightly beyond the front ends of such plugs. Those front ends are then ground down to make the front end of each fiber with the front surface of its corresponding plug and to assure that such front end is normal to the plug's axis.
Next, the two terminal plugs for the fibers are brought into bearing relation with a guide means such that the front ends of the plugs are in end-to-end relation and the axes of the two plugs are aligned by the guide means to be co-parallel. For the purpose of making the mentioned splice, the exteriors of the two plugs are close enough to true circular cylindrical that such plugs can be treated as being perfect cylinders having plug axes from which, in each plug, all radii from its axis to its cylindrical surface has the same length. At the front end of the plug, on the other hand, the optical fiber end is usually radially displaced from the plug axis by a certain eccentricity as a result of inherent imprecision in manufacturing the plug and assembling the plug and fiber.
In those circumstances, it has been found that, by providing in the guide means for an offsetting of the axes of the two plugs (so that they are not coaxial) while maintaining those axes aligned co-paralle, and by rotating one or both of the plugs around its axis, the ends of the two optical fibers can be brought into a registration producing an optical splicing thereof which is good enough so that infra red or other "light" radiation can be transmitted from one to the other fiber with very little loss.
A connector employing the technique just described to optically splice two optical fibers is disclosed in U.S. Pat. No. 4,545,644 issued Oct. 8, 1985 in the name of George F. DeVeau Jr. et a. and assigned to AT&T Bell Laboratories ("DeVeau"). Such connector comprises an alignment bracket provided by a rectangular piece of sheet metal bent to conform to the shape of the outline of a triangular prism. The two ends of the sheet around the periphery of the prism are separated from each other one one side of the prism by a gap parallel to the prism's axis. Within the triangular prismatic interior of the bracket, three cylindrical glass rods are at the three corners of the triangular cross-section of the bracket, and are in spaced parallel relation to provide a central passage extending through the bracket inwardly of the three rods.
The two fiber terminating plugs are inserted into opposite ends of the passage and are held in end-to-end aligned relation therein by the resilient force of the bracket as exerted on the plugs through the rods. These rods have flats formed on them. By relative angular rotation of the two plugs about their axes, the optical fibers terminated by these plugs are caused to become optically spliced.
In the DeVeau connector, the glass rods which align the plugs are fastened by adhesive to the enveloping resilient sheet metal bracket. The use of adhesive to provide such fastening has the disadvantages among others that the bond between the rods and the bracket is not always reliable, the bonding power of the adhesive material tends to deteriorate with time, and the introducing into the connector of the adhesive and its subsequent curing undesirably adds to the time and effort required to manufacture the DeVeau connector.